The Origin and Evolution of Mammals - Moodle

50 THE ORIGIN AND EVOLUTION OF MAMMALS
Figure 3.14 (continued).
(d)
(e) (f) (g)
to 59, with a strong suspicion than several of these
are still synonymous.
Lystrosaurus (Fig. 3.14(c)) is the most remarkable
pristerodontoid, indeed the most remarkable dicynodont
in several ways. It is a tusked form clearly
related to Dicynodon (Fig. 3.14(a)), but has exaggerated
the shortening of both the palate and the
temporal region of the skull, resulting in a strongly
downturned snout. The Late Permian South African
Kwazulusaurus (Fig. 3.14(b)) has a skull structure
Kannemeyereria
Tetragonius Stahleckeria Ischigualastia
intermediate in form between Dicynodon and
Lystrosaurus and Maisch (2002) consequently interprets
it as a basal lystrosaurid. Lystrosaurus itself is
the only actual genus of dicynodont that is known
to have survived the end-Permian, having been
identified in the latest Permian as well as the earliest
Triassic deposits (Smith 1995; King and Jenkins
1997), when it became supremely abundant in terms
of both numbers and geographical distribution.
In South Africa, well over 90% of specimens